It all began when Rymill attended a personal training session shortly after giving birth. "Obviously you want to get back to your pre-baby weight," Rymill's PT told her.

But that wasn't the reason at all.

Rymill, who played roller derby for seven years, wanted her strong and healthy body back. Due to a high-risk pregnancy she hadn't exercised for nine months, but after giving birth she wanted to rectify that.

After the personal training session, the conversation stuck in Rymill's mind. Understandably, she was pissed off.

It was then that she penned a Facebook post, which has since been shared more than 7,000 times (and counting).

She wrote: "Post pregnant women are told they look good if they return to their pre-baby body quickly leading to the assumption that they look bad if they keep the extra weight.

"Skinny people are envied for their lack of fat or shamed for apparently starving themselves. Voluptuous women are either labelled fat and shamed or they're labelled brave for being comfortable in their own skin.

"There is always pressure."

She continued: "No one is comfortable in their own skin 100% of the time. Constantly labelling people and piling expectations associated with these labels on them is harmful to everyone, including those doing the labelling.

"What we should be worrying about is if people are ok, not what they look like.

"So here I am. I may not be magazine ready, my nana undies and bedtime nursing bra are certainly not going to be rocking a runway anytime soon, my hair is greasy, I have no makeup on, my body is squishy and plentiful, I'm not even sure I'm totally ok.

"But I am strong. My body is healthy. Hell, I am badass as fuck!"

Her post has received an overwhelmingly positive response. One user wrote: "You are incredible and you have a rocking body! What a great post for all mums and mums-to-be. And how lucky your little ones are to have such a strong and confident role model in this life."

While another added: "Good on you Mel Rymill, it's such fucking bullshit to think we all want to have the same body shape all the way throughout our lives."

Rymill's words of wisdom have since inspired an online body image revolution, with other women flocking to share their own underwear selfies with the hashtag #badassundies.